In the Joseon Dynasty period, the kingdom was enveloped in a political maelstrom. Cheo-seon was born as a posthumous child and separated from his mother immediately. He was raised by Weol-hwa and the old Swe-gwi, who ran the eunuch school. When he meets So-hwa, the daughter of a powerful noble, he falls in love with her immediately. He voluntarily becomes a eunuch to be close to So-hwa and is assigned to work for Cho Chi-gyeom, a senior eunuch. Entering the royal palace, he sees King, Sung-Jong and So-hwa spend their first night together. He becomes So-hwa’s loyal protector. As the political battles rage on among the courtesans and wives in the palace, So-hwa is chosen by the king to be his queen and Cheo-seon vows to be her loyal servant. But So-hwa is eventually dethroned as the queen and leaves the palace in disgrace. Cheo-seon helplessly watches these events unfold and he secretly helps So-hwa. But in a cruel twist of fate, he is the one chosen to execute So-hwa’s death sentence by serving her a bowlful of poison. After So-hwa dies, he looks after her son King, Yeonsangun as if he were his own son....